A Carbon-Based DNA Framework Nano-Bio Interface for Biosensing with High Sensitivity and a High Signal-to-Noise Ratio.

Biosensing interface based on screen-printed carbon electrodes (SPCE) has been widely used for electrochemical biosensors in the field of medical diagnostics, food safety, and environmental monitoring. Nevertheless, SPCE always has a rough surface, which is easy to result in the disorder of nucleic acid capture probes, the nonspecific adsorption of signaling probes, the steric hindrance of target binding, and decrease in the signal-to-noise ratio and sensitivity of biosensors. So far, it still remains extremely challenging to develop high-efficiency carbon-based biosensing interfaces, especially for DNA probe-based assembly and functionalization. In this paper, we first used a specific DNA framework, DNA tetrahedron to solve the defects of the carbon interface, improving the biosensing ability of SPCE. With covalent coupling, the DNA tetrahedron could be immobilized on the carbon surface. Biosensing probe sequences extending from the DNA tetrahedron can be changed for different target molecules. We demonstrated that the improved SPCE could be applied for the detection of a variety of bioactive molecules. Typically, we designed gap hybridization, aptamer "sandwich" and aptamer competition reduction strategy for the detection of miRNA-141, thrombin, and ATP, respectively. High signal-to-noise ratio, sensitivity, and specificity were obtained for all of these kinds. Especially, the DNA tetrahedron-modified SPCE can work well with serum samples. The carbon-based DNA framework nano-bio interface would expand the use of SPCE and make electrochemical biosensors more available and valuable in clinical diagnosis.